Paper coating



fluent ed June 7, 1938 PAPER COATING Philip s. Barnhart, Westflcld, Mass, minimto Westfield River Paper Company, Inc., Russell,

Mass, acorporation of Massachusetts No Drawing. Application June 19, 1930,

Serial No. 86,081

4 Claims. (01. 134-11) This invention relates to paper coating, and particularly to coating paper of the type known as glassine paper.

Glassine paper as manufactured is not impervious to air or moisture and in order to impart these qualities to the paper it is necessary to coat the paper on one or both sides with a film of coating material. Moreover, a properly constituted coating composition increases the transparency of the paper.

The coating material must be so-constituted that it will not detract from the transparencyor flexibility of the paper and will give a glossy film.

that is not tacky and will be moisture-proof or moisture resistant. Obviously, these requirements materially limit the range of and propertions of the ingredients which are available.

This invention has for its salient object to provide a coating composition for glassine paper so constituted that it will be flexible, non-tacky,

transparent, glossy and highly moisture resistant or moisture-proof.

Another object of the invention is. to provide a composition so constituted that it will be flexii ble, non-tacky, glossy, transparent and moisture resistant and can be applied in a thin film or coating to sheet material, such as gla'ssine paper.

Further objects of the invention will appear from the following specification.

In the composition are embodied, generally the following ingredients, namely, a base, resin, wax and plasticizer, combined in the desired proportions.

As a base ch substance containing both tri-chloro and tetrachloro, derivatives of rubber.

This particular type of chlorinated rubber has for itsadvantage the ability to give relatively high concentrations in solutions without a resultant or L correspondingly high viscosity.

ever, requires resin to give a glossy film and a plasticizer to render it soft and flexible.

For resins, a combination of resins having different properties is used andv preferably a combination of I glycerol abietate and para-couma- 'rone. Gylcerol abietate is madeby heating glycerine and rosin toa certain temperature for a i predetermined lengthof time.- Para-coumarone resin comprises polymerized coumarone and indone. The para-coumarone is used to offset a tendency of the glycerol abietate to become tacky,-

It should .be understood, however, that other suitable resins may be used.

Parafllne wax having a melting point 'gfeapproximately 143-145 1". is used .as the wax.

rinated rubber is utilized, this This base, how-- Various plasticizers may be used. such as di-' butyl phthalate, .di -ethyl phthalate, tri-cresyi phosphateor like substances;

, The ingredients are preferably combined in the following approximate proportions, which may, g however, be varied to give thedesired qualities:

. Percent Chlorinated rubber L4". 4040' Glycerol abietate 20-25 Paramnewax,143-145 r 2- v Di-butyl phthalate s 15-21 Para-coumarone, Cum. ;..1 5-13 After these ingredients are combined in these approximate proportions the composition is dis- 1} solved in any suitable hydro-carbon solvent, such as benzol, toluol, xylol, etc. to give a solution of "the desired viscosity.

This solution is applied to the sur'faceor sur- I faces of the sheet to be coated by roll coating or ,1 in any other suitable manner. v

For instance, 'the glassine vsheet, preferably plasticized, is humidified to increase its moisture content, if suflicient moisture is not present therein, and. the surface or surfaces thereof are coated a with the solution by roll coaters. The sheet is then passed through a dryer which evaporates I the solvent and dries the coated surfaces.

A coating composition having the ingredients described forms a thin, glossy highly transparao ent, flexible, moisture' proof or moisture resistant film. Moreover, this composition has marked advantages from the standpoint of economy. For instance, coating compositions having a liltroceliulose base require the use of relatively i I high priced solvents and the concentration is limited to approximately one-half that-obtain- 1 able with the chlorinated rubber base.

Although one tain preferred ingredients and proportions thereof have been described, it should be understood that equivalent ingredients may be used and the proportions may be varied without departing from the spirit or scope of the invention, as eX- 45 pressed in the following claims..

' What I claim is: V

1. A coating composition comprising chloriated rubber 40-50%, resin, comprising glycerol abietate and para coumarone 25-38%, psraflne so wax 2-'l%.and a plasticizer'15-21%. 2. A coating composition comprising chlorinated rubber 40-50%, resin, comprising glycerol abietate and para coumarone, 25-38%, Mamie wax-24% and di-butyl phthalate 15-21%.

speciilc embodiment and cert 3. A coating composition comprising chlorinoted rubber 40-50%. glycerol abletate 20-25%, para-coumarone 5-13 parafllne wax 2-7%, and

s a plasticizer 15-21%.

4. A flowable coating-comprising chlorlneted rubber, resin, comprising glycerol abletate and 5 -13% para coumarone, parafllne wax. a plasti-' PHIL]? S. BARNHART. 

